percona-server-5.7.36-39/sql/item_strfunc.h

#ifndef ITEM_STRFUNC_INCLUDED
#define ITEM_STRFUNC_INCLUDED

/* Copyright (c) 2000, 2021, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */


/* This file defines all string functions */
#include "crypt_genhash_impl.h"       // CRYPT_MAX_PASSWORD_SIZE
#include "item_func.h"                // Item_func

class MY_LOCALE;

class Item_str_func :public Item_func
{
  typedef Item_func super;

public:
  Item_str_func() :Item_func() { decimals=NOT_FIXED_DEC; }
  explicit Item_str_func(const POS &pos) :super(pos) { decimals=NOT_FIXED_DEC; }

  Item_str_func(Item *a) :Item_func(a) {decimals=NOT_FIXED_DEC; }
  Item_str_func(const POS &pos, Item *a) :Item_func(pos, a)
  {decimals=NOT_FIXED_DEC; }

  Item_str_func(Item *a,Item *b) :Item_func(a,b) { decimals=NOT_FIXED_DEC; }
  Item_str_func(const POS &pos, Item *a,Item *b) :Item_func(pos, a,b)
  { decimals=NOT_FIXED_DEC; }

  Item_str_func(Item *a, Item *b, Item *c) :Item_func(a, b, c)
  { decimals=NOT_FIXED_DEC; }
  Item_str_func(const POS &pos, Item *a, Item *b, Item *c)
    :Item_func(pos, a,b,c)
  { decimals=NOT_FIXED_DEC; }

  Item_str_func(Item *a, Item *b, Item *c, Item *d) :Item_func(a, b, c, d)
  {decimals=NOT_FIXED_DEC; }
  Item_str_func(const POS &pos, Item *a, Item *b, Item *c, Item *d)
    :Item_func(pos, a,b,c,d)
  {decimals=NOT_FIXED_DEC; }

  Item_str_func(Item *a, Item *b, Item *c, Item *d, Item* e)
    :Item_func(a, b, c, d, e)
  {decimals=NOT_FIXED_DEC; }
  Item_str_func(const POS &pos, Item *a, Item *b, Item *c, Item *d, Item* e)
    :Item_func(pos, a, b, c, d, e)
  {decimals=NOT_FIXED_DEC; }

  Item_str_func(List<Item> &list) :Item_func(list) {decimals=NOT_FIXED_DEC; }
  Item_str_func(const POS &pos, PT_item_list *opt_list)
    :Item_func(pos, opt_list)
  {decimals=NOT_FIXED_DEC; }

  longlong val_int();
  double val_real();
  my_decimal *val_decimal(my_decimal *);
  bool get_date(MYSQL_TIME *ltime, my_time_flags_t fuzzydate)
  {
    return get_date_from_string(ltime, fuzzydate);
  }
  bool get_time(MYSQL_TIME *ltime)
  {
    return get_time_from_string(ltime);
  }
  enum Item_result result_type () const { return STRING_RESULT; }
  void left_right_max_length();
  bool fix_fields(THD *thd, Item **ref);
  String *val_str_from_val_str_ascii(String *str, String *str2);
};


/*
  Functions that return values with ASCII repertoire
*/
class Item_str_ascii_func :public Item_str_func
{
  String ascii_buf;
public:
  Item_str_ascii_func() :Item_str_func()
  { collation.set_repertoire(MY_REPERTOIRE_ASCII); }

  Item_str_ascii_func(Item *a) :Item_str_func(a)
  { collation.set_repertoire(MY_REPERTOIRE_ASCII); }
  Item_str_ascii_func(const POS &pos, Item *a) :Item_str_func(pos, a)
  { collation.set_repertoire(MY_REPERTOIRE_ASCII); }

  Item_str_ascii_func(Item *a,Item *b) :Item_str_func(a,b)
  { collation.set_repertoire(MY_REPERTOIRE_ASCII); }
  Item_str_ascii_func(const POS &pos, Item *a,Item *b) :Item_str_func(pos, a,b)
  { collation.set_repertoire(MY_REPERTOIRE_ASCII); }

  Item_str_ascii_func(Item *a,Item *b,Item *c) :Item_str_func(a,b,c)
  { collation.set_repertoire(MY_REPERTOIRE_ASCII); }
  Item_str_ascii_func(const POS &pos, Item *a,Item *b,Item *c)
    :Item_str_func(pos, a,b,c)
  { collation.set_repertoire(MY_REPERTOIRE_ASCII); }

  String *val_str(String *str)
  {
    return val_str_from_val_str_ascii(str, &ascii_buf);
  }
  virtual String *val_str_ascii(String *)= 0;
};


class Item_func_md5 :public Item_str_ascii_func
{
  String tmp_value;
public:
  Item_func_md5(const POS &pos, Item *a) :Item_str_ascii_func(pos, a) {}
  String *val_str_ascii(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "md5"; }
};


class Item_func_sha :public Item_str_ascii_func
{
public:
  Item_func_sha(const POS &pos, Item *a) :Item_str_ascii_func(pos, a) {}
  String *val_str_ascii(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "sha"; }
};

class Item_func_sha2 :public Item_str_ascii_func
{
public:
  Item_func_sha2(const POS &pos, Item *a, Item *b)
    :Item_str_ascii_func(pos, a, b)
  {}
  String *val_str_ascii(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "sha2"; }
};

class Item_func_to_base64 :public Item_str_ascii_func
{
  String tmp_value;
public:
  Item_func_to_base64(const POS &pos, Item *a) :Item_str_ascii_func(pos, a) {}
  String *val_str_ascii(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "to_base64"; }
};

class Item_func_from_base64 :public Item_str_func
{
  String tmp_value;
public:
  Item_func_from_base64(const POS &pos, Item *a) :Item_str_func(pos, a) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "from_base64"; }
};


class Item_func_aes_encrypt :public Item_str_func
{
  typedef Item_str_func super;
public:
  Item_func_aes_encrypt(const POS &pos, Item *a, Item *b)
    :Item_str_func(pos, a, b)
  {}
  Item_func_aes_encrypt(const POS &pos, Item *a, Item *b, Item *c)
    :Item_str_func(pos, a, b, c)
  {}

  virtual bool itemize(Parse_context *pc, Item **res);
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "aes_encrypt"; }
};

class Item_func_aes_decrypt :public Item_str_func
{
  typedef Item_str_func super;
public:
  Item_func_aes_decrypt(const POS &pos, Item *a, Item *b)
    :Item_str_func(pos, a, b)
  {}
  Item_func_aes_decrypt(const POS &pos, Item *a, Item *b, Item *c)
    :Item_str_func(pos, a, b, c)
  {}

  virtual bool itemize(Parse_context *pc, Item **res);
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "aes_decrypt"; }
};


class Item_func_random_bytes : public Item_str_func
{
  typedef Item_str_func super;

  /** limitation from the SSL library */
  static const longlong MAX_RANDOM_BYTES_BUFFER;
public:
  Item_func_random_bytes(const POS &pos, Item *a) : Item_str_func(pos, a)
  {}

  virtual bool itemize(Parse_context *pc, Item **res);
  void fix_length_and_dec();
  String *val_str(String *a);

  const char *func_name() const
  {
    return "random_bytes";
  }

};

class Item_func_concat :public Item_str_func
{
  String tmp_value;
public:
  Item_func_concat(const POS &pos, PT_item_list *opt_list)
      : Item_str_func(pos, opt_list), tmp_value("", 0, collation.collation) {}
  Item_func_concat(Item *a, Item *b)
      : Item_str_func(a, b), tmp_value("", 0, collation.collation) {}
  Item_func_concat(const POS &pos, Item *a, Item *b)
      : Item_str_func(pos, a, b), tmp_value("", 0, collation.collation) {}

  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "concat"; }
};

class Item_func_concat_ws :public Item_str_func
{
  String tmp_value;
public:
  Item_func_concat_ws(List<Item> &list)
      : Item_str_func(list), tmp_value("", 0, collation.collation) {}
  Item_func_concat_ws(const POS &pos, PT_item_list *opt_list)
      : Item_str_func(pos, opt_list), tmp_value("", 0, collation.collation) {}

  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "concat_ws"; }
  table_map not_null_tables() const { return 0; }
};

class Item_func_reverse :public Item_str_func
{
  String tmp_value;
public:
  Item_func_reverse(Item *a) :Item_str_func(a) {}
  Item_func_reverse(const POS &pos, Item *a) :Item_str_func(pos, a) {}

  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "reverse"; }
};


class Item_func_replace :public Item_str_func
{
  String tmp_value,tmp_value2;
  /// Holds result in case we need to allocate our own result buffer.
  String tmp_value_res;
public:
  Item_func_replace(const POS &pos, Item *org,Item *find,Item *replace)
    :Item_str_func(pos, org,find,replace)
  {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "replace"; }
};


class Item_func_insert :public Item_str_func
{
  String tmp_value;
  /// Holds result in case we need to allocate our own result buffer.
  String tmp_value_res;
public:
  Item_func_insert(const POS &pos,
                   Item *org, Item *start, Item *length, Item *new_str)
    :Item_str_func(pos, org,start,length,new_str)
  {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "insert"; }
};


class Item_str_conv :public Item_str_func
{
protected:
  uint multiply;
  my_charset_conv_case converter;
  String tmp_value;
public:
  Item_str_conv(const POS &pos, Item *item) :Item_str_func(pos, item) {}
  String *val_str(String *);
};


class Item_func_lower :public Item_str_conv
{
public:
  Item_func_lower(const POS &pos, Item *item) :Item_str_conv(pos, item) {}
  const char *func_name() const { return "lower"; }
  void fix_length_and_dec();
};

class Item_func_upper :public Item_str_conv
{
public:
  Item_func_upper(const POS &pos, Item *item) :Item_str_conv(pos, item) {}
  const char *func_name() const { return "upper"; }
  void fix_length_and_dec();
};


class Item_func_left :public Item_str_func
{
  String tmp_value;
public:
  Item_func_left(const POS &pos, Item *a,Item *b) :Item_str_func(pos, a,b) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "left"; }
};


class Item_func_right :public Item_str_func
{
  String tmp_value;
public:
  Item_func_right(const POS &pos, Item *a,Item *b) :Item_str_func(pos, a,b) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "right"; }
};


class Item_func_substr :public Item_str_func
{
  typedef Item_str_func super;

  String tmp_value;
public:
  Item_func_substr(Item *a,Item *b) :Item_str_func(a,b) {}
  Item_func_substr(const POS &pos, Item *a,Item *b) :super(pos, a,b) {}

  Item_func_substr(Item *a,Item *b,Item *c) :Item_str_func(a,b,c) {}
  Item_func_substr(const POS &pos, Item *a,Item *b,Item *c) :super(pos, a, b, c)
  {}

  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "substr"; }
};


class Item_func_substr_index :public Item_str_func
{
  String tmp_value;
public:
  Item_func_substr_index(const POS &pos, Item *a,Item *b, Item *c)
    :Item_str_func(pos, a, b, c)
  {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "substring_index"; }
};


class Item_func_trim :public Item_str_func
{
public:
  /**
    Why all the trim modes in this enum?
    We need to maintain parsing information, so that our print() function
    can reproduce correct messages and view definitions.
   */
  enum TRIM_MODE
  {
    TRIM_BOTH_DEFAULT,
    TRIM_BOTH,
    TRIM_LEADING,
    TRIM_TRAILING,
    TRIM_LTRIM,
    TRIM_RTRIM
  };

private:
  String tmp_value;
  String remove;
  const TRIM_MODE m_trim_mode;
  const bool m_trim_leading;
  const bool m_trim_trailing;

public:
  Item_func_trim(Item *a, Item *b, TRIM_MODE tm)
    : Item_str_func(a,b), m_trim_mode(tm),
      m_trim_leading(trim_leading()), m_trim_trailing(trim_trailing())
  {}

  Item_func_trim(const POS &pos, Item *a, Item *b, TRIM_MODE tm)
    : Item_str_func(pos, a,b), m_trim_mode(tm),
      m_trim_leading(trim_leading()), m_trim_trailing(trim_trailing())
  {}

  Item_func_trim(Item *a, TRIM_MODE tm)
    : Item_str_func(a), m_trim_mode(tm),
      m_trim_leading(trim_leading()), m_trim_trailing(trim_trailing())
  {}

  Item_func_trim(const POS &pos, Item *a, TRIM_MODE tm)
    : Item_str_func(pos, a), m_trim_mode(tm),
      m_trim_leading(trim_leading()), m_trim_trailing(trim_trailing())
  {}

  bool trim_leading() const
  {
    return
      m_trim_mode == TRIM_BOTH_DEFAULT ||
      m_trim_mode == TRIM_BOTH ||
      m_trim_mode == TRIM_LEADING ||
      m_trim_mode == TRIM_LTRIM;
  }

  bool trim_trailing() const
  {
    return
      m_trim_mode == TRIM_BOTH_DEFAULT ||
      m_trim_mode == TRIM_BOTH ||
      m_trim_mode == TRIM_TRAILING ||
      m_trim_mode == TRIM_RTRIM;
  }

  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const
  {
    switch(m_trim_mode) {
    case TRIM_BOTH_DEFAULT: return "trim";
    case TRIM_BOTH:         return "trim";
    case TRIM_LEADING:      return "ltrim";
    case TRIM_TRAILING:     return "rtrim";
    case TRIM_LTRIM:        return "ltrim";
    case TRIM_RTRIM:        return "rtrim";
    }
    return NULL;
  }
  virtual void print(String *str, enum_query_type query_type);
};


/*
  Item_func_password -- new (4.1.1) PASSWORD() function implementation.
  Returns strcat('*', octet2hex(sha1(sha1(password)))). '*' stands for new
  password format, sha1(sha1(password) is so-called hash_stage2 value.
  Length of returned string is always 41 byte. To find out how entire
  authentication procedure works, see comments in password.c.
*/

class Item_func_password :public Item_str_ascii_func
{
  char m_hashed_password_buffer[CRYPT_MAX_PASSWORD_SIZE + 1];
  unsigned int m_hashed_password_buffer_len;
  bool m_recalculate_password;
public:
  Item_func_password(Item *a) : Item_str_ascii_func(a)
  {
    m_hashed_password_buffer_len= 0;
    m_recalculate_password= false;
  }
  String *val_str_ascii(String *str);
  void fix_length_and_dec();
  const char *func_name() const { return "password"; }
};


class Item_func_des_encrypt :public Item_str_func
{
  String tmp_value,tmp_arg;
public:
  Item_func_des_encrypt(const POS &pos, Item *a) :Item_str_func(pos, a) {}
  Item_func_des_encrypt(const POS &pos, Item *a, Item *b)
    : Item_str_func(pos, a, b)
  {}
  String *val_str(String *);
  void fix_length_and_dec()
  {
    maybe_null=1;
    /* 9 = MAX ((8- (arg_len % 8)) + 1) */
    max_length = args[0]->max_length + 9;
  }
  const char *func_name() const { return "des_encrypt"; }
};

class Item_func_des_decrypt :public Item_str_func
{
  String tmp_value;
public:
  Item_func_des_decrypt(const POS &pos, Item *a) :Item_str_func(pos, a) {}
  Item_func_des_decrypt(const POS &pos, Item *a, Item *b)
    : Item_str_func(pos, a, b)
  {}
  String *val_str(String *);
  void fix_length_and_dec()
  {
    maybe_null=1;
    /* 9 = MAX ((8- (arg_len % 8)) + 1) */
    max_length= args[0]->max_length;
    if (max_length >= 9U)
      max_length-= 9U;
  }
  const char *func_name() const { return "des_decrypt"; }
};

class Item_func_encrypt :public Item_str_func
{
  typedef Item_str_func super;

  String tmp_value;

  /* Encapsulate common constructor actions */
  void constructor_helper()
  {
    collation.set(&my_charset_bin);
  }
public:
  Item_func_encrypt(const POS &pos, Item *a) :Item_str_func(pos, a)
  {
    constructor_helper();
  }
  Item_func_encrypt(const POS &pos, Item *a, Item *b): Item_str_func(pos, a, b)
  {
    constructor_helper();
  }

  virtual bool itemize(Parse_context *pc, Item **res);
  String *val_str(String *);
  void fix_length_and_dec() { maybe_null=1; max_length = 13; }
  const char *func_name() const { return "encrypt"; }
  bool check_gcol_func_processor(uchar *int_arg)
  { return true; }
};

#include "sql_crypt.h"


class Item_func_encode :public Item_str_func
{
private:
  /** Whether the PRNG has already been seeded. */
  bool seeded;
  /// Holds result in case we need to allocate our own result buffer.
  String tmp_value_res;
protected:
  SQL_CRYPT sql_crypt;
public:
  Item_func_encode(const POS &pos, Item *a, Item *seed)
    :Item_str_func(pos, a, seed)
  {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "encode"; }
protected:
  virtual void crypto_transform(String *);
private:
  /** Provide a seed for the PRNG sequence. */
  bool seed();
};


class Item_func_decode :public Item_func_encode
{
public:
  Item_func_decode(const POS &pos, Item *a, Item *seed)
    :Item_func_encode(pos, a, seed)
  {}
  const char *func_name() const { return "decode"; }
protected:
  void crypto_transform(String *);
};


class Item_func_sysconst :public Item_str_func
{
  typedef Item_str_func super;

public:
  Item_func_sysconst()
  { collation.set(system_charset_info,DERIVATION_SYSCONST); }
  explicit Item_func_sysconst(const POS &pos) : super(pos)
  { collation.set(system_charset_info,DERIVATION_SYSCONST); }

  Item *safe_charset_converter(const CHARSET_INFO *tocs);
  /*
    Used to create correct Item name in new converted item in
    safe_charset_converter, return string representation of this function
    call
  */
  virtual const Name_string fully_qualified_func_name() const = 0;
  bool check_gcol_func_processor(uchar *int_arg)
  { return true; }
};


class Item_func_database :public Item_func_sysconst
{
  typedef Item_func_sysconst super;

public:
  explicit Item_func_database(const POS &pos) :Item_func_sysconst(pos) {}

  virtual bool itemize(Parse_context *pc, Item **res);

  String *val_str(String *);
  void fix_length_and_dec()
  {
    max_length= MAX_FIELD_NAME * system_charset_info->mbmaxlen;
    maybe_null=1;
  }
  const char *func_name() const { return "database"; }
  const Name_string fully_qualified_func_name() const
  { return NAME_STRING("database()"); }
};


class Item_func_user :public Item_func_sysconst
{
  typedef Item_func_sysconst super;

protected:
  bool init (const char *user, const char *host);
  type_conversion_status save_in_field_inner(Field *field, bool no_conversions)
  {
    return save_str_value_in_field(field, &str_value);
  }

public:
  Item_func_user()
  {
    str_value.set("", 0, system_charset_info);
  }
  explicit Item_func_user(const POS &pos) : super(pos)
  {
    str_value.set("", 0, system_charset_info);
  }

  virtual bool itemize(Parse_context *pc, Item **res);

  String *val_str(String *)
  {
    assert(fixed == 1);
    return (null_value ? 0 : &str_value);
  }
  bool fix_fields(THD *thd, Item **ref);
  void fix_length_and_dec()
  {
    max_length= (USERNAME_LENGTH +
                 (HOSTNAME_LENGTH + 1) * SYSTEM_CHARSET_MBMAXLEN);
  }
  const char *func_name() const { return "user"; }
  const Name_string fully_qualified_func_name() const
  { return NAME_STRING("user()"); }
};


class Item_func_current_user :public Item_func_user
{
  typedef Item_func_user super;

  Name_resolution_context *context;

public:
  explicit Item_func_current_user(const POS &pos) : super(pos) {}

  virtual bool itemize(Parse_context *pc, Item **res);

  bool fix_fields(THD *thd, Item **ref);
  const char *func_name() const { return "current_user"; }
  const Name_string fully_qualified_func_name() const
  { return NAME_STRING("current_user()"); }
};


class Item_func_soundex :public Item_str_func
{
  String tmp_value;
public:
  Item_func_soundex(Item *a) :Item_str_func(a) {}
  Item_func_soundex(const POS &pos, Item *a) :Item_str_func(pos, a) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "soundex"; }
};


/**
  This class handles two forms of the same function:

  <string> = ST_GEOHASH(<point>, <maxlength>);
  <string> = ST_GEOHASH(<longitude>, <latitude>, <maxlength>)

  It returns an encoded geohash string, no longer than <maxlength> characters
  long. Note that it might be shorter than <maxlength>.
*/
class Item_func_geohash :public Item_str_ascii_func
{
private:
  /// The latitude argument supplied by the user (directly or by a POINT).
  double latitude;
  /// The longitude argument supplied by the user (directly or by a POINT).
  double longitude;
  /// The maximum output length of the geohash, supplied by the user.
  uint geohash_max_output_length;

  /**
    The maximum input latitude. For now, this is set to 90.0. It can be
    changed to support a different range than the normal [90, -90].
  */
  const double max_latitude;

  /**
    The minimum input latitude. For now, this is set to -90.0. It can be
    changed to support a different range than the normal [90, -90].
  */
  const double min_latitude;

  /**
    The maximum input longitude. For now, this is set to 180.0. It can be
    changed to support a different range than the normal [180, -180].
  */
  const double max_longitude;

  /**
    The minimum input longitude. For now, this is set to -180.0. It can be
    changed to support a different range than the normal [180, -180].
  */
  const double min_longitude;

  /**
    The absolute upper limit of geohash output length. User will get an error
    if they supply a max geohash length argument greater than this.
  */
  const uint upper_limit_output_length;
public:
  Item_func_geohash(const POS &pos, Item *point, Item *length)
    :Item_str_ascii_func(pos, point, length), max_latitude(90.0),
    min_latitude(-90.0), max_longitude(180.0), min_longitude(-180.0),
    upper_limit_output_length(100)
  {}
  Item_func_geohash(const POS &pos, Item *longitude, Item *latitude,
                    Item *length)
    :Item_str_ascii_func(pos, longitude, latitude, length), max_latitude(90.0),
    min_latitude(-90.0), max_longitude(180.0), min_longitude(-180.0),
    upper_limit_output_length(100)
  {}
  String *val_str_ascii(String *);
  void fix_length_and_dec();
  bool fix_fields(THD *thd, Item **ref);
  const char *func_name() const { return "st_geohash"; }
  char char_to_base32(char char_input);
  void encode_bit(double *upper_value, double *lower_value,
                  double target_value, char *char_value, int bit_number);
  bool fill_and_check_fields();
  bool check_valid_latlong_type(Item *ref);
  static bool is_item_null(Item *item);
};


class Item_func_elt :public Item_str_func
{
public:
  Item_func_elt(const POS &pos, PT_item_list *opt_list)
    :Item_str_func(pos, opt_list)
  {}
  double val_real();
  longlong val_int();
  String *val_str(String *str);
  void fix_length_and_dec();
  const char *func_name() const { return "elt"; }
};


class Item_func_make_set :public Item_str_func
{
  typedef Item_str_func super;

  Item *item;
  String tmp_str;

public:
  Item_func_make_set(const POS &pos, Item *a, PT_item_list *opt_list)
    :Item_str_func(pos, opt_list), item(a)
  {}

  virtual bool itemize(Parse_context *pc, Item **res);
  String *val_str(String *str);
  bool fix_fields(THD *thd, Item **ref)
  {
    assert(fixed == 0);
    bool res= ((!item->fixed && item->fix_fields(thd, &item)) ||
               item->check_cols(1) ||
               Item_func::fix_fields(thd, ref));
    maybe_null|= item->maybe_null;
    return res;
  }
  void split_sum_func(THD *thd, Ref_ptr_array ref_pointer_array,
                      List<Item> &fields);
  void fix_length_and_dec();
  void update_used_tables();
  const char *func_name() const { return "make_set"; }

  bool walk(Item_processor processor, enum_walk walk, uchar *arg)
  {
    if ((walk & WALK_PREFIX) && (this->*processor)(arg))
      return true;
    if (item->walk(processor, walk, arg))
      return true;
    for (uint i= 0; i < arg_count; i++)
    {
      if (args[i]->walk(processor, walk, arg))
        return true;
    }
    return ((walk & WALK_POSTFIX) && (this->*processor)(arg));
  }

  Item *transform(Item_transformer transformer, uchar *arg);
  virtual void print(String *str, enum_query_type query_type);
};


class Item_func_format :public Item_str_ascii_func
{
  String tmp_str;
  MY_LOCALE *locale;
public:
  Item_func_format(const POS &pos, Item *org, Item *dec)
    : Item_str_ascii_func(pos, org, dec)
  {}
  Item_func_format(const POS &pos, Item *org, Item *dec, Item *lang)
    : Item_str_ascii_func(pos, org, dec, lang)
  {}

  MY_LOCALE *get_locale(Item *item);
  String *val_str_ascii(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "format"; }
  virtual void print(String *str, enum_query_type query_type);
};


class Item_func_char :public Item_str_func
{
public:
  Item_func_char(const POS &pos, PT_item_list *list) :Item_str_func(pos, list)
  { collation.set(&my_charset_bin); }
  Item_func_char(const POS &pos, PT_item_list *list, const CHARSET_INFO *cs)
    : Item_str_func(pos, list)
  { collation.set(cs); }
  String *val_str(String *);
  void fix_length_and_dec()
  {
    max_length= arg_count * 4;
  }
  const char *func_name() const { return "char"; }
};


class Item_func_repeat :public Item_str_func
{
  String tmp_value;
public:
  Item_func_repeat(const POS &pos, Item *arg1,Item *arg2)
    :Item_str_func(pos, arg1,arg2)
  {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "repeat"; }
};


class Item_func_space :public Item_str_func
{
public:
  Item_func_space(const POS &pos, Item *arg1) :Item_str_func(pos, arg1) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "space"; }
};


class Item_func_rpad :public Item_str_func
{
  String tmp_value, rpad_str;
public:
  Item_func_rpad(const POS &pos, Item *arg1, Item *arg2, Item *arg3)
    :Item_str_func(pos, arg1, arg2, arg3)
  {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "rpad"; }
};


class Item_func_lpad :public Item_str_func
{
  String tmp_value, lpad_str;
public:
  Item_func_lpad(const POS &pos, Item *arg1, Item *arg2, Item *arg3)
    :Item_str_func(pos , arg1, arg2, arg3)
  {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "lpad"; }
};


class Item_func_conv :public Item_str_func
{
public:
  Item_func_conv(const POS &pos, Item *a,Item *b,Item *c)
    :Item_str_func(pos, a,b,c)
  {}
  const char *func_name() const { return "conv"; }
  String *val_str(String *);
  void fix_length_and_dec();
};


class Item_func_hex :public Item_str_ascii_func
{
  String tmp_value;
public:
  Item_func_hex(const POS &pos, Item *a) :Item_str_ascii_func(pos, a) {}
  const char *func_name() const { return "hex"; }
  String *val_str_ascii(String *);
  void fix_length_and_dec()
  {
    collation.set(default_charset());
    decimals=0;
    fix_char_length(args[0]->max_length * 2);
  }
};

class Item_func_unhex :public Item_str_func
{
  String tmp_value;
public:
  Item_func_unhex(const POS &pos, Item *a) :Item_str_func(pos, a)
  {
    /* there can be bad hex strings */
    maybe_null= 1;
  }
  const char *func_name() const { return "unhex"; }
  String *val_str(String *);
  void fix_length_and_dec()
  {
    collation.set(&my_charset_bin);
    decimals=0;
    max_length=(1+args[0]->max_length)/2;
  }
};


#ifndef NDEBUG
class Item_func_like_range :public Item_str_func
{
protected:
  String min_str;
  String max_str;
  const bool is_min;
public:
  Item_func_like_range(const POS &pos, Item *a, Item *b, bool is_min_arg)
    :Item_str_func(pos, a, b), is_min(is_min_arg)
  { maybe_null= 1; }
  String *val_str(String *);
  void fix_length_and_dec()
  {
    collation.set(args[0]->collation);
    decimals=0;
    max_length= MAX_BLOB_WIDTH;
  }
};


class Item_func_like_range_min :public Item_func_like_range
{
public:
  Item_func_like_range_min(const POS &pos, Item *a, Item *b)
    :Item_func_like_range(pos, a, b, true)
  { }
  const char *func_name() const { return "like_range_min"; }
};


class Item_func_like_range_max :public Item_func_like_range
{
public:
  Item_func_like_range_max(const POS &pos, Item *a, Item *b)
    :Item_func_like_range(pos, a, b, false)
  { }
  const char *func_name() const { return "like_range_max"; }
};
#endif


class Item_char_typecast :public Item_str_func
{
  int cast_length;
  const CHARSET_INFO *cast_cs, *from_cs;
  bool charset_conversion;
  String tmp_value;
public:
  Item_char_typecast(Item *a, int length_arg, const CHARSET_INFO *cs_arg)
    :Item_str_func(a), cast_length(length_arg), cast_cs(cs_arg) {}
  Item_char_typecast(const POS &pos, Item *a, int length_arg,
                     const CHARSET_INFO *cs_arg)
    :Item_str_func(pos, a), cast_length(length_arg), cast_cs(cs_arg)
  {}
  enum Functype functype() const { return TYPECAST_FUNC; }
  bool eq(const Item *item, bool binary_cmp) const;
  const char *func_name() const { return "cast_as_char"; }
  String *val_str(String *a);
  void fix_length_and_dec();
  virtual void print(String *str, enum_query_type query_type);
};


class Item_func_binary :public Item_str_func
{
public:
  Item_func_binary(const POS &pos, Item *a) :Item_str_func(pos, a) {}
  String *val_str(String *a)
  {
    assert(fixed == 1);
    String *tmp=args[0]->val_str(a);
    null_value=args[0]->null_value;
    if (tmp)
      tmp->set_charset(&my_charset_bin);
    return tmp;
  }
  void fix_length_and_dec()
  {
    collation.set(&my_charset_bin);
    max_length=args[0]->max_length;
  }
  virtual void print(String *str, enum_query_type query_type);
  const char *func_name() const { return "cast_as_binary"; }
  enum Functype functype() const { return TYPECAST_FUNC; }
};


class Item_load_file :public Item_str_func
{
  typedef Item_str_func super;

  String tmp_value;
public:
  Item_load_file(const POS &pos, Item *a) :Item_str_func(pos, a) {}

  virtual bool itemize(Parse_context *pc, Item **res);
  String *val_str(String *);
  const char *func_name() const { return "load_file"; }
  void fix_length_and_dec()
  {
    collation.set(&my_charset_bin, DERIVATION_COERCIBLE);
    maybe_null=1;
    max_length=MAX_BLOB_WIDTH;
  }
  bool check_gcol_func_processor(uchar *int_arg)
  { return true; }
};


class Item_func_export_set: public Item_str_func
{
 public:
  Item_func_export_set(const POS &pos, Item *a, Item *b, Item* c)
    :Item_str_func(pos, a, b, c)
  {}
  Item_func_export_set(const POS &pos, Item *a, Item *b, Item* c, Item* d)
    :Item_str_func(pos, a, b, c, d)
  {}
  Item_func_export_set(const POS &pos,
                       Item *a, Item *b, Item* c, Item* d, Item* e)
    :Item_str_func(pos, a, b, c, d, e)
  {}
  String  *val_str(String *str);
  void fix_length_and_dec();
  const char *func_name() const { return "export_set"; }
};

class Item_func_quote :public Item_str_func
{
  String tmp_value;
public:
  Item_func_quote(const POS &pos, Item *a) :Item_str_func(pos, a) {}
  const char *func_name() const { return "quote"; }
  String *val_str(String *);
  void fix_length_and_dec()
  {
    collation.set(args[0]->collation);
    ulong max_result_length= (ulong) args[0]->max_length * 2 +
                                  2 * collation.collation->mbmaxlen;
    max_length= std::min<ulong>(max_result_length, MAX_BLOB_WIDTH);
  }
};

class Item_func_conv_charset :public Item_str_func
{
  bool use_cached_value;
  String tmp_value;
public:
  bool safe;
  const CHARSET_INFO *conv_charset; // keep it public
  Item_func_conv_charset(const POS &pos, Item *a, const CHARSET_INFO *cs)
  : Item_str_func(pos, a)
  { conv_charset= cs; use_cached_value= 0; safe= 0; }
  Item_func_conv_charset(Item *a, const CHARSET_INFO *cs,
                         bool cache_if_const) :Item_str_func(a)
  {
    assert(is_fixed_or_outer_ref(args[0]));

    conv_charset= cs;
    if (cache_if_const && args[0]->const_item())
    {
      uint errors= 0;
      String tmp, *str= args[0]->val_str(&tmp);
      if (!str || str_value.copy(str->ptr(), str->length(),
                                 str->charset(), conv_charset, &errors))
        null_value= 1;
      use_cached_value= 1;
      str_value.mark_as_const();
      safe= (errors == 0);
    }
    else
    {
      use_cached_value= 0;
      /*
        Conversion from and to "binary" is safe.
        Conversion to Unicode is safe.
        Other kind of conversions are potentially lossy.
      */
      safe= (args[0]->collation.collation == &my_charset_bin ||
             cs == &my_charset_bin ||
             (cs->state & MY_CS_UNICODE));
    }
  }
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "convert"; }
  virtual void print(String *str, enum_query_type query_type);
};

class Item_func_set_collation :public Item_str_func
{
  typedef Item_str_func super;

  LEX_STRING collation_string;
public:
  Item_func_set_collation(const POS &pos, Item *a,
                          const LEX_STRING &collation_string_arg)
    :super(pos, a, NULL), collation_string(collation_string_arg)
  {}

  virtual bool itemize(Parse_context *pc, Item **res);
  String *val_str(String *);
  void fix_length_and_dec();
  bool eq(const Item *item, bool binary_cmp) const;
  const char *func_name() const { return "collate"; }
  enum Functype functype() const { return COLLATE_FUNC; }
  virtual void print(String *str, enum_query_type query_type);
  Item_field *field_for_view_update()
  {
    /* this function is transparent for view updating */
    return args[0]->field_for_view_update();
  }
};

class Item_func_charset :public Item_str_func
{
public:
  Item_func_charset(const POS &pos, Item *a) :Item_str_func(pos, a) {}
  String *val_str(String *);
  const char *func_name() const { return "charset"; }
  void fix_length_and_dec()
  {
     collation.set(system_charset_info);
     max_length= 64 * collation.collation->mbmaxlen; // should be enough
     maybe_null= 0;
  };
  table_map not_null_tables() const { return 0; }
};

class Item_func_collation :public Item_str_func
{
public:
  Item_func_collation(const POS &pos, Item *a) :Item_str_func(pos, a) {}
  String *val_str(String *);
  const char *func_name() const { return "collation"; }
  void fix_length_and_dec()
  {
     collation.set(system_charset_info);
     max_length= 64 * collation.collation->mbmaxlen; // should be enough
     maybe_null= 0;
  };
  table_map not_null_tables() const { return 0; }
};

class Item_func_weight_string :public Item_str_func
{
  typedef Item_str_func super;

  String tmp_value;
  uint flags;
  uint nweights;
  uint result_length;
  Field *field;
  bool as_binary;
public:
  Item_func_weight_string(const POS &pos, Item *a, uint result_length_arg,
                          uint nweights_arg, uint flags_arg,
                          bool as_binary_arg= false)
  :Item_str_func(pos, a), field(NULL), as_binary(as_binary_arg)
  {
    nweights= nweights_arg;
    flags= flags_arg;
    result_length= result_length_arg;
  }

  virtual bool itemize(Parse_context *pc, Item **res);

  const char *func_name() const { return "weight_string"; }
  bool eq(const Item *item, bool binary_cmp) const;
  String *val_str(String *);
  void fix_length_and_dec();
  virtual void print(String *str, enum_query_type query_type);
};

class Item_func_crc32 :public Item_int_func
{
  String value;
public:
  Item_func_crc32(const POS &pos, Item *a) :Item_int_func(pos, a)
  { unsigned_flag= 1; }
  const char *func_name() const { return "crc32"; }
  void fix_length_and_dec() { max_length=10; }
  longlong val_int();
};

class Item_func_uncompressed_length : public Item_int_func
{
  String value;
public:
  Item_func_uncompressed_length(const POS &pos, Item *a) :Item_int_func(pos, a)
  {}
  const char *func_name() const{return "uncompressed_length";}
  void fix_length_and_dec() { max_length=10; }
  longlong val_int();
};

#ifdef HAVE_COMPRESS
#define ZLIB_DEPENDED_FUNCTION ;
#else
#define ZLIB_DEPENDED_FUNCTION { null_value=1; return 0; }
#endif

class Item_func_compress: public Item_str_func
{
  String buffer;
public:
  Item_func_compress(const POS &pos, Item *a):Item_str_func(pos, a){}
  void fix_length_and_dec(){max_length= (args[0]->max_length*120)/100+12;}
  const char *func_name() const{return "compress";}
  String *val_str(String *) ZLIB_DEPENDED_FUNCTION
};

class Item_func_uncompress: public Item_str_func
{
  String buffer;
public:
  Item_func_uncompress(const POS &pos, Item *a): Item_str_func(pos, a) {}
  void fix_length_and_dec(){ maybe_null= 1; max_length= MAX_BLOB_WIDTH; }
  const char *func_name() const{return "uncompress";}
  String *val_str(String *) ZLIB_DEPENDED_FUNCTION
};

class Item_func_uuid: public Item_str_func
{
  typedef Item_str_func super;
public:
  Item_func_uuid(): Item_str_func() {}
  explicit
  Item_func_uuid(const POS &pos): Item_str_func(pos) {}

  virtual bool itemize(Parse_context *pc, Item **res);
  void fix_length_and_dec()
  {
    collation.set(system_charset_info,
                  DERIVATION_COERCIBLE, MY_REPERTOIRE_ASCII);
    fix_char_length(UUID_LENGTH);
  }
  const char *func_name() const{ return "uuid"; }
  String *val_str(String *);
  bool check_gcol_func_processor(uchar *int_arg)
  { return true; }
};

class Item_func_gtid_subtract: public Item_str_ascii_func
{
  String buf1, buf2;
public:
  Item_func_gtid_subtract(const POS &pos, Item *a, Item *b)
    :Item_str_ascii_func(pos, a, b)
  {}
  void fix_length_and_dec();
  const char *func_name() const{ return "gtid_subtract"; }
  String *val_str_ascii(String *);
};

#endif /* ITEM_STRFUNC_INCLUDED */